• Title/Summary/Keyword: resonant column and torsional shear test

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Analysis of Static and Dynamic Characteristics of Reinforced Roadbed Materials (철도 강화노반재료의 정ㆍ동적 특성 분석)

  • 황선근;신민호;이성혁;이시한;최찬용
    • Journal of the Korean Society for Railway
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    • v.3 no.1
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    • pp.34-41
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    • 2000
  • The analysis of static and dynamic characteristics of reinforced roadbed materials was performed through model and laboratory tests. The strength characteristic of reinforced roadbed materials such as HMS-25 and soil were investigated through the unconfined axial compression test, the model soil box test and the combined resonant column and torsional shear test. The unconfined axial compression strength of HMS-25 shows a steady increasement in strength due to the chemical hardening reaction between HMS-25 and water. The result of model soil box test reveals that railroad roadbed of HMS-25 is better than that of soil in several aspects, such as, bearing capacity and settlement. The combined resonant column and torsional shear test result indicates that shear modulus of HMS-25 and soil increase with the power of 0.5 to the confining pressure and linear relationship to normalized shear modulus and damping ratio.

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A Solution to Large Strain Resonant Column and Torsional Shear Tests Apparatus (대변형율 시험을 위한 공진주/비틂전단 시험기의 해결방안)

  • Bae, Yoon-Shin
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.3C
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    • pp.103-108
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    • 2011
  • In this study, the limitations of large strain resonant column and torsional shear tests apparatus are described and solutions to the limitations are also described. The limitations are rotational distance, limited torque, and measurable deformation system, respectively. To resolve the rotational distance, the bottom platen was modified. And the four-armed drive plate was modified into eight-armed drive plate and the drive coil connection was changed to obtain powerful torque.

Evaluation of Applicability of HMS-25 as the Railroad Roadbed Material (철도 노반재로서의 수경성 입도 조정 고로슬래그(HMS-25)의 적용성 평가)

  • 황선근;이성혁;이시한;최찬용
    • Journal of the Korean Geotechnical Society
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    • v.16 no.1
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    • pp.157-165
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    • 2000
  • The applicability and performance of HMS-25 as the railroad roadbed materials were evaluated through the model and laboratory tests. The uniaxial compression test of HMS-25, model soil box test, and combined resonant column and torsional shear test were performed for static and dynamic analysis of railroad roadbed. The uniaxial compression test result of HMS-25 shows steady increase in strength due to hardening chemical reaction between HMS-25 and water. The result of model soil box test reveals that railroad roadbed of HMS-25 is better than that of soil in several aspects such as bearing capacity and settlement. The combined resonant column and torsional that shear test result indicates that shear modulus of HMS-25 increases with the power of 0.5 to the confining pressure and that shear modulus increases with the increase of curing period.

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Deformational Characteristics of Dry Sand Using Resonant Column / Torsional Shear Testing Equipment (공진주/비틂 전단(RC/TS)시험기를 이용한 건조 사질토의 변형특성)

  • 김동수
    • Geotechnical Engineering
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    • v.11 no.1
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    • pp.101-112
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    • 1995
  • Deformational characteristics of soils, often expressed in terms of shear modulus and material damping ratios, are important parameters in the design of soil-structure systems subjected to cyclic and dynamic loadings. In this paper, deformational characteristics of dry sand at small to intermediate strains were investigated using resonant column/torsional shear(RC 175) apparatus. Both resonant column(dynamic) and torsional shear (cyclic) tests were performed in a sequential series on the same specimen. With the modification of motion monitoring system, the elastic zone, where the stress strain relationship is independent of loading cycles and strain amplitude, was veri tied and hysteretic damping was found even in this zone. At strains above cyclic threshold, shear modulus increases and damping ratio decreases with increasing number of loading cycles. Moduli and damping ratios of dry sand are independent of loading frequency and values obtained from pseudostatic torsional shear tests are Identical with the values from the dynamic resonant column test, provided the effect of number of loading cycles is considered in the conlparison. Therefore, deformational characteristics determined by RC/TS tests may be applied in both dynamic and static analyses of soil-structure systems.

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Evaluation of Shear Wave Velocity of Engineering Fill by Resonant Column and Torsional Shear Tests (공진주와 비틂전단시험에 의한 성토지반의 전단파속도 추정에 관한 연구)

  • Park, Jong-Bae;Sim, Young-Jong;Jung, Jong-Suk;Park, Yong-Boo
    • Land and Housing Review
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    • v.2 no.4
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    • pp.387-395
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    • 2011
  • According to the seismic design criteria for structural buildings in Korea, the ground is classified into 5 types based on the average shear wave velocity measured from elastic wave tests on site and seismic load applied to the structure is estimated. However, elastic wave tests in site, however, on the engineering fill, cannot be performed during the construction period. Therefore, to evaluate shear wave velocity considering field conditions, resonant column (RC) and torsional shear (TS) tests are performed and compared with various elastic wave test results. As a result, if confining pressure for the tests using engineering fill are considered properly, we can obtain similar results comparing with those of elastic wave tests. In addition, by considering the effect of maximum shear modulus and confining pressure by RC/TS tests, n values shows typical values ranging from 0.434 to 0.561 so that utilization of RC/TS tests can be useful to infer shear modulus in field.

Evaluation of Seismic Response Characteristics of Hong-Seong Area based on In-Situ and Laboratory Tests (현장 및 실내시험에 기초한 홍성지역 지진응답특성 평가)

  • 박덕근;김교원
    • The Journal of Engineering Geology
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    • v.11 no.1
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    • pp.25-35
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    • 2001
  • For the ground resrxmse analysis, both in-situ and laboratory testing techniques such as downhole, SASW, resonant column and torsional shear tests were perlormed for Hong-Seong area. The grOlmd upper 30m is classified as SD since it has an average shear wave velocity as 209m/s. The response specLrums obtained by site-specific analyses generally satisfied the seismic code, but near the resonance period the motion was evaluated to be higher than the code.

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Measurement of $G_{max}$ of Sands Using Bender Element in Resonant Column and Torsional Shear Equipment (공진주/비틂전단 시험 및 벤더엘리먼트 시험을 이용한 사질토 지반의 최대전단탄성계수 평가)

  • Kim Dong-Soo;Youn Jun-Ung;Lee Sei-Hyun;Choo Yun-Wook
    • Journal of the Korean Geotechnical Society
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    • v.21 no.10
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    • pp.17-25
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    • 2005
  • The bender element method is an experimental technique to determine very small strain ($<10^{-3}\%$), elastic shear modulus of a soil, $G_{max}$ by measuring the velocity of shear wave propagation through a sample. Bender elements have been applied as versatile transducers to measure small strain modulus of wet or dry soils in various laboratory apparatus. In this paper, bender element (BE), resonant column (RC) and torsional shear (TS) tests were performed on Toyoura sand at various testing conditions using the modified Stokoe type RC/TS testing equipment capable of performing BE test. Based on the results, applicabilities of the testing method using bender element were evaluated by comparing the values of $G_{max}$ obtained from RC/TS and BE testing methods. For more dependable evaluation, the loading frequency of each testing method was considered for the results obtained for samples in saturated condition by adapting Biot's theory.

Dynamic Deformation Characteristics of Granite Weathered Soils Using RC/TS Tests (공진주/비틂전단시험을 이용한 화강풍화지반의 동적변형특성)

  • Kim, Dong-Soo;Ko, Dong-Hee;Youn, Jun-Ung
    • Journal of the Korean GEO-environmental Society
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    • v.5 no.1
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    • pp.35-46
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    • 2004
  • In Korea, around one - third of the country is occupied by granite, and granite weathered soils are widely distributed. Most of the research on this soil has been performed using reconstituted specimens because of the extreme difficulty of undisturbed sampling due to the sensitive particle structures. Therefore, the comparisons of deformational characteristics, which is expressed in terms of shear and Young's moduli and damping ratio, obtained from the undisturbed and reconstituted specimens are important for the reliable understanding of soil behavior. In this study, the resonant column and torsional shear tests were performed on granite weathered soils in Korea, and the deformation characteristics of undisturbed and reconstituted soil on granite weathered soils were evaluated and compared.

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Deformational Characteristics of Cohesive Soils Using Resonant Column / Torsional Shear Testing Equipment (공진주/비틂 전단(RC/TS)시험기를 이용한 점성토의 변형특성)

  • 김동수
    • Geotechnical Engineering
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    • v.11 no.1
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    • pp.113-126
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    • 1995
  • Both resonant column (RC) and torsional shear(TS) tests were performed at small to intermediate strain levels to investigate deformational characteristics of cohesive soils. The effects of variables such as strain amplitude, loading frequency, and number of loading cycles were studied. Plasticity index was found to be an important variables in evaluating these effects. Soils tested include undisturbed silts and clays and compacted subgrade soils. At small strains below the elastic threshold, shear modulus is independent of number of loading cycles and strain amplitude. Small strain material damping exists wi th ranges be tween 1.1% and 1.7% for 75 tests. The elastic threshold strain increases as confining pressure and plasticity index increases. Above the cyclic threshold strain, the modulus of cohesive soil decreases with increasing number of cycles while damping ratio is almost independent of number of load cycles. Moduli and damping ratios of cohesive soils obtanined by RC test are higher than those from 75 test because of the frequency effect. Shear modulus of cohesive soil increases linearly as a function of the logarithm of loading frequency.

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An Anisotropic Hardening Elasto-Plastic Constitutive Model for the Behavior at Small-to-Large Strain Conditions (미소변형률 및 대변형률 조건의 거동에 대한 비등방경화 탄소성 구성모델)

  • 오세붕;권기철;정순용;김동수
    • Journal of the Korean Geotechnical Society
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    • v.16 no.1
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    • pp.65-73
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    • 2000
  • An elasto-plastic constitutive model was proposed, in which the behavior at small-to-large strain level can be modeled. The proposed model is based on the anisotropic hardening description with the generalization of isotropic hardening rule and the total stress concept. From a mathematical approach it was proved that the model includes the previous successful models. The model was verified by a series of resonant column tests, torsional shear tests and triaxial tests, and the proposed model predicted small-to-large strain behavior more consistently and accurately than the hyperbolic model and the Ramberg-Osgood model for a weathered granitic soil. In addition, the nonlinearity under small strain condition was predicted appropriately for the torsional shear test results.

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